EP285 You Can’t Control a System That’s Open - Ken Allison on HVAC and the Building Envelope (August 2026)
Quotes from the episode:
“I don't need the house to breathe. I need the people to.”
“You can't control a system that's open.”
“I would just go make them comfortable. And let them know the added benefit is that they're going to spend less on energy.”
What happens when an HVAC contractor fixes the equipment, but the customer still isn’t comfortable?
In this episode of Building HVAC Science, Bill Spohn talks with Ken Allsion of Insulation Distributors (IDI) about why HVAC contractors are uniquely positioned to recognize—and potentially solve - problems with the building envelope. Ken argues that comfort complaints often blamed on heating and cooling equipment actually begin with uncontrolled air leakage, poorly installed insulation, and mechanical systems operating outside the thermal envelope.
Ken lays out a practical path for HVAC companies interested in adding envelope work without trying to turn every technician into a building scientist. It starts simply: train technicians to recognize obvious problems such as daylight, wind-washed insulation, unsealed attic hatches, and other signs of leakage. From there, contractors can progress to blower-door testing and infrared diagnostics, and eventually tackle more sophisticated envelope improvements.
A recurring theme is that insulation only performs as intended when air movement is controlled. Ken explains why nominal R-value can be misleading, how small areas of poorly performing insulation can dramatically reduce whole-assembly performance, and why he prioritizes air sealing at the top and bottom of the building before worrying about walls.
The conversation also explores an important business opportunity. Ken sees attic insulation removal, air sealing, and blow-back as relatively low-barrier services that complement HVAC work while allowing specialized crews - not highly trained HVAC technicians—to perform the labor.
Most importantly, Ken challenges contractors to rethink what they're really selling. Rather than leading with energy savings, start with what homeowners actually care about: comfort, healthier indoor conditions, and a house that works better. Reduced energy use becomes a valuable consequence of fixing the building—not necessarily the reason for doing it.
Website link: https://www.idi-insulation.com/industries/hvac
IDI’s podcast: https://www.idi-insulation.com/podcast/
IDI’s Training Calendar: https://www.idi-insulation.com/training/
The Matt Risinger video Ken mentioned: https://youtu.be/1BcqeQJqp08?si=jVwKLJQcULbcbYbM
Nate Adma’s Home Comfort book mentioned: https://trutechtools.com/The-Home-Comfort-Book
The Attic Queen! : https://www.atticqueen.com/
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This episode was recorded in August 2026.
